1. Field of the Invention
The present invention relates generally to an industrial endoscope and, more particularly, to an arc-shaped flexible printed circuit film type endoscope using an imaging device in which a flexible printed circuit film is connected to a head housing accommodating a charge coupled device (CCD) camera or a complementary metal-oxide-semiconductor (CMOS) sensor as the imaging device so that the endoscope can be mounted to a small space such as a robot to easily inspect the interior of a narrow heat transfer tube, and the endoscope has a small bending radius to be conveniently handled in the small space.
2. Description of the Related Art
Generally, a plurality of heat transfer tubes is mounted on a secondary side's tube sheet of a steam generator installed in a nuclear power plant, with very narrow gaps formed between the heat transfer tubes. Here, sludge or impurities may enter the gaps between the heat transfer tubes, thus causing damage to the heat transfer tubes.
Therefore, in order to prevent the heat transfer tubes from being damaged by the sludge or impurities, visual inspection is periodically conducted. The visual inspection is performed through endoscopy using an endoscope camera which is mounted to a micro robot or the like.
Endoscopy is the non-destructive inspection method of visually inspecting the interior of a human body organ or an object without impairing the human body organ or the object, by inserting an insertion tube into the human body organ or the object.
Endoscopes are typically classified into medical and industrial endoscopes according to the object to be inspected. Among them, the manufacture of the industrial endoscope is difficult because its insertion part is small and thin.
Thus, in Korea, the industrial endoscope has not been researched and developed nor has it come onto the market yet. The supply of most endoscopes depends on imports.
The industrial endoscope includes an input-output unit for visually inspecting an object, a light source, and an insertion tube. Since most inspection instruments are too large to be inspected by an inspector, a lot of time, labor and expenses are required.
Further, the industrial endoscope adopts an analogue method. Thus, in order to store photographed images, photographs must be printed through chemical treatment, and the inspected result must be read via image equipment which is installed in an inspection site, so that there are restrictions of time and space. Further, since it is impossible to transmit data of the inspected result over a network, it is impossible share the data in real time.
In consideration of these aspects, as the conventional industrial endoscope which has been used to visually inspect the heat transfer tubes, an endoscope which has an industrial endoscope camera (including an endoscope camera and a CCD sensor) and a belt or a chain having a cable therein has been proposed.
The conventional endoscope is problematic in that the chain or belt is thick, so that it occupies a large space when rolled into a circular shape, and therefore it is difficult to mount the endoscope to a small space such as a robot so as to inspect the interior of a narrow heat transfer tube.
Further, the conventional belt- or circular cable-type endoscope camera is problematic in that when it is constructed to be very thin, it is too flexible, so that it is difficult to maintain strength of linear extension.
However, the endoscope according to the present invention uses an arc-shaped flexible thin foil, so that linearity is ensured in shape even though the endoscope comprises a very thin film, thus the endoscope has both linearity and flexibility.
Further, the endoscope camera, the cable, an illumination part and other parts are integrally installed in the chain- or belt-type feeding means, so that a bending radius is large. Thus, it is difficult to mount the conventional endoscope to a narrow space such as a robot and to handle it.
Meanwhile, in order to photograph a small space, there has been proposed Japanese Patent Laid-Open Publication No. 2006-319401, which is entitled “Remote Inspection System”.
The remote inspection system includes a CMOS image sensor as an imaging device of a video camera. By manipulating a power supply for a video camera and white LED which is connected in a conduction state through a flexible spiral metal tube to an inspection head having the white LED for illumination, the remote inspection system photographs a narrow space.
Thus, a photographing unit includes the CMOS sensor and the illumination part, so that it is possible to photograph and inspect a small space. However, since a circuit means or a transmission means for processing or transmitting a photographed image cannot be formed on the spiral metal tube itself, the circuit means or the transmission means for processing or transmitting the photographed image must be provided separately from the spiral metal tube, thus inconveniencing a manufacturer.